CA1172130A

CA1172130A - Liquid detergent compositions

Info

Publication number: CA1172130A
Application number: CA000400208A
Authority: CA
Inventors: Anthony F. Martin
Original assignee: Procter and Gamble Co
Current assignee: Procter and Gamble Co
Priority date: 1981-04-03
Filing date: 1982-03-31
Publication date: 1984-08-07
Also published as: JPS5811596A; EP0062371B1; DE3264512D1; EP0062371A1; ATE14142T1

Abstract

ABSTRACT

The present invention provides a clear single-phase enzyme-free dishwashing liquid composition comprising a C14-C17 alkane sulfonate, C10-C16 alkyl ethoxy sulphates containing from 1 to 6 ethoxy groups per mole of alkyl sulphate or mixtures thereof with C10-C16 alkyl benzene sulfonates, and from 0.35% -0.7%
magnesium ion, wherein there are specified limits on the maximum amounts of inorganic salts that can be present in the composition.

Description

1~72~3~ -LIQUID DETERGENT CO~lPOSITIONS

, Field OL the Invention - . This inventi.on relates to a~ueous liquid dishwashing : detergent compositions and especially to substantially unbuilt hand dishwashing detergent compositions incorpora~ing alkane sulphonate surfactant together with a source.o magnesium ions.
~ ~ Background of the Invention ::~ The use of.magnesium salts and magnesium surfactants such as alkyl sulphates; alkyl ether sulphate;s and alkyl ~benzene sulphonates in dishwashing detergent formulations : : is knownr and.British Patent Specification Nos~. 1,5~4,441, 1,551-,074 and 2,010,893A are representative disclosures of the sta~e of the art.~ The art teaches that thes~
formulations have enhanced performance, particularly when used in water of low mineral hardness. Liquid detergent compositions containing alkane sulpho~at~sur~ac.~an~s are also known in the art.~ Compositions~primarily intended for fabric washing are described:ih~B;.P. 1,054,217, ~ 1,329,508 and 1,291~l63/ th~ last named of which disclose~s : ~0 a mixture o~ an alkane sulphonate, an ethox~lated alXyl ; : su~phate, and a proteolytic enzyme together with an en2yme~s.tab;1ising aqent in the form of a calci.um or magnes~um salt, specifi.cally the:ac.etate or t~e chlori~
Enzymes are not however customary:components of hand dishwashing liquid detergent formulations, particularly : . in formulations where skin mildness is an importan~
~ in-use requirement.
; Dishwashing liquid detergent compositions contaîning alkane sulphonates are also kno-~n, e~amples of such 30 :disclosures including those in B.P. l,339,069, l,382~295, 1,451,228 and l,567,q21. However products mad-e in ,' . ' , ' ~L7;~

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accordance with these teachings have all been found to be non-optimal in one area of performance or another eg.
raw material cost, phase stability on storage, sudsing in water of high or low mineral hardness, effect on hands, suds profile, physical stability under cyclic temperature conditions etc ..
The present invention.is concerned with an aqueous hand dishwashing detergent composition that is enz~me- -free. More particularly, it co~cerns an enz~me-free dishwashing detergent composition containing alkane sulphonate surfactan~, the sudsing performance of which has been enhanced by the incorporation of speci~ic levels of magnesium ion. - .
According to the present invention there is provided a clear single-phase enzyme-free dishwa~hing liquid -composition comprising 20-40% of a C14-C17 alkane 5ul-phonate, 5-15% of an anionic surfactan:~ selected from .. . water soluble C10-Cl6 alkyl ethoxy sulphates containin~
from 1-6 ethoxy groups per mole of alkyl sulphate, and mixtures thereof with water soluble C10-Cl6 alkyl ben2en~
sulphonate~, 0-5% of a suds boosteL sel.ected from C10-Cl6 k 1 mides C C16 alkyl C2-C3 alkanol 10 16 alkyl di Cl-C3 alkyl or di C2-C3 hydroxyalkyI amine oxiaes and from 0.35%-0.7% magnesium ion, the composition containing `5 no more than 1.75~ by weight of chloxide ions or more:
thanØ35% by weight of inorganic sulphate ions provided that whexe chloride ions are also present ~he level of sulphate ions should not exceed 0.25~ by weight, the counter ions other than magnesium necessary to provide a pH of 6.0-7.5 being selected from sodium, potassium, ammoni~m and alkanolammonium.
- Preferably the composition comprises 22-36-~ C16 17 alkanesulphona.te,6-12% C12 14 alkyl ethoxy sulphate and O.S~
magnesi~m ion with a ma~im~m o~ 0.5% inorganic sait anions.
Secondary alkane sulpho~ates use~ul in the pr~sent invention preferably have from 13 to 18 caxbon atoms per 1172~3C~
.

molecule, and most desirably 13 to 15, and are characterised by a high solubility in water compared to alkyl aryl sulphonates and other sulphuric acid reaction products used for dishwashing detergent compositions. These S sulphonates are preferably prepared by subjecting a cut of paraffin, corresponding to the chain lengths specified above, to the action of-sulphur dioxide and oxygen in accordance with the well-known sulphoxidation process.
The product of this reaction is a secondary sulphonic 10 acid which is then neutralized with a suitable base to provide a water-soluble secondary alkyl sulphonate.
Similar secondary alkyl sulphonates may be obtained by other methods, e.g. by the sulphochlorination method in which chlorine and sulphur dioxide are reacted with ~5 paraffins in the presence of actinic light, the resulting sulphonyl chlorides being hydrolyzed and neutralized to form the secondary alkyl sulphonates. Whatever technique ~ ~ is employed, it is normally desirable to produce the sulphonate as the monosulphonate, having no unreacted starting hydrocarbon or having only a limited proportion thereof present and with ~ittle or no inorganic salt by-product. Similarly, the proportions of disulphonate or higher sulphonated material will be minimized but some may be present. The monosulphonate may be terminally sulphonated or the sulphonate group may be joined on the

2-carbon ox other carbon of the linear chain. Similarly, any accompanying disulphonate, usually produced when an excess of sulphonating agent is present, may have th~
sulphonate groups distributed over different carbon atoms ~0 of the paraffin base, and mixtures of the monosulphonates and disulphonatzs may be pxesent.
Mixtures of monoalkane sulphonates wherein the alkanes are of 14 and 15 carbon atoms are particularly preferred wherein the sulphonates are present in the weight ratio of C14 to Cl~ paraffins in the range from 1:3 to 3:1, L7~3~

preferably 1:2 to 2:1. Surprisingly, this particular mixture produces detergents which clean dishes better and which suds longer, especially in hard water, than other mixtures of paraffin sulphonates, e.g. those of 13 to 17 carbon atoms. This is also true, to a lesser extent, of the individual components of the C14 and C15 mixture.
The alkane sulphonates are used at a level of from 20 to 40~, more generally at a level of from 22% to 36%, preferably from 24% to 34% and most preferably from 26~ to 32~ by weight of the composition.
The alkyl ethoxy sulphates used in the compositions of the present invention can be represented by the formula RO(c2H4o)nso3x where R is a C10-Cl6 preferably 12-15 linear or branched chain, primary alkyl group, n is a value from 1 to 6 pref-erably 2-5 and X is a water soluble cation. C10-Cl6 alcohols, derived from natural fats or Ziegler olefin build-up or OXO synthesis form suitable sources for the alkyl group. Examples of synthetically derived materials include Dobano ~ 23 (RTM) sold by Shell Chemicals (UK) Ltd., Ethy ~ 24 sold by the Ethyl Corporation, a blend of C13-C15 alcohols in the ratio 67~ C13, 33% C15 sold under the trade name Lutensol~ by BASF GmbH and Synperonic (RTM) by IC~ Ltd, and Lial~ 125 sold by Liquichimica Italiana. Examples of naturally occuring materials from which the alcohols can be derived are coconut oil and palm kernel oil and the corresponding fatty acids.
The alkyl ethoxy sulphates are used in an amount of from 5~ to 15~ by weight of the composition, and, where they constitute the only anionic surfactant species other than the alkane sulphonate, are normally used at from 10%
to 15~ by weightO
The alkyl ethoxy sulphates can also be used in admixture with water soluble linear or branched C10-Cl6 ,i ., ~ . .

~172~3(~

alkyl benzene sulphonates. In such alkyl benzene sulphonates, the alkyl group is preferably linear and contains 11-13 carbon atoms, a material with an average carbon chain length of 11.8 being most preferred. The phenyl isomer distribution, ie. the point of attach]nent of the alkyl chain to the benzene nucleus, is not critical but alkyl benzenes having a high 2-phenyl iso-mer content are preferred.
Where mixtures of the alkyl ethoxy sulphates and alkyl benzene sulphonates are used the levels of alkyl benzene sulphonate should be such that the ratio of the combined weight of alkane sulphonate and alkyl benzene sulphonate to the weight of alkyl ethoxy sulphate should not exceed 10:1 and prefer-ably should not exceed 5:1. In practice the level of alkyl benzene sulphonate will not usually exceed 12% by weight of the composition and will normalIy be in the range 4%-10% by weight. Correspondingly, the overall alkyl ethoxy sulphate level will be reduced where such mixtures are employed.
An essential component of the formulation is a source of magnesium ions at a level to provide 0.35% to 0.70%
by weight of magnesium ion in the product, preferably 0.40%
to 0.60~ by weight. Subject to the requirement that the final product is a clear single-phase liq~id, the magnesium ion can be provided either by addition of a water soluble magensium salt such as the chloride or acetate to the formulation, or by the use of magnesium oxide)or hydro~ide slurry as a com-ponent of the neutralising medium for one or other of the anionic surfactants during manufacture.
The requirement that the final product is a clear, single phase liquid creates a constraint on the level of dis-solved inorganic salts that can be tolerated by the formula-tion without phase separation or crystallisation occuring.
By 'tolerated' is meant the ability of a ~17Z13(~

formulation to withstand storage without t,he formation of other solid or li~uid phases~ A minimum requirement is that storage at ambient temperature (v'iz 20C) should not result in such phase separation but preferably the temperature at which phase separation or crystal deposition , occurs should necessitate cooling of the omposition to a sub-a~ient temperature. This sub-a~ient temperature is conventionaIly known as the chill point temperature of a liquid deter~ent composition and'is defined as that 10 temperature below which solid inorganic crystals separate from the composi,tion on storage. It has been-found'that, in order to achieve acceptable chill point temperatures, the composition of the present invention should not contain more than 1.75% by weight of chloride ions or 15 more than 0.35~ of sulphate ions, provided that where ' chloride ions are also present the level of sulphate ions , should not exceed 0.25%'by weight and preferably should ' not ~ceed 0.15%''by weight.' Formulations having low chill point temperatures, i.e. < ~C, Xave sulphate levels at ', 20 the lower end of this range.
' The'tolerance-of the formulations to inorganic salt level has been found to be dependent on the inorganic salt type and also on the counter ion types present in the formula,tions,. Thus fo~mulations in which the counter 25 ~ons ~other than the magnesium) are mainly or exclusively ammonium'or potassium are-more tolerant to inorganic -salts,than those where the cG~nter ions are main~y or exclusively sodium ions. Furt~er~.~re chloride ions can be tolerated at much higher levels than sulphate ions, It has been found, for example, that in a formu-lation compr~sing 30% MC15-C17 paraffin sulphonate 15% ~C12~E0)3 sulphate 10% ethyl alcohol solvent with 0.475~ Magnesium ion added as ma~nesium 1~ 2 hydroxide forming part cf the counter ion M, when M is ammonium, the level of sulphate ion that the formulation can tolerate without precipitation is 0.35 by weight of the formulation whereas when M is sodium, 5 the level of sulphate ion that can be tolerated is no more than 0.20~ by weight. By con-.ràst in the same system, 1.75% chloride ion can be toleratea, irrespe~tive of the counter ion e~ployed, althou~h at this level of chloride ion the presence of sulphate ions in excess o~
io about 0.15% by weight will lead to deposition of a crystalline precipitate.
~ he commerciai production of paraffin sulphonates, alkyl benzene sulphonates and al~yl ether sulphates uses techniques that are well known in the art and involves 15 the use of sulph(on)ating agents such as S03, oleum, chlorosulphonic acid or S02, all of which gi~e rise to -- _- residues of sulphates and~or chlorides in the active materials. The levels of sulphates and/or chlorides can be minimised by careful control of the sulph(on~ation 20 conditians, and by air, or inert gas, spargi~g of the acid sulph(on)ate products but in general at least 0~1%
by weight of inorganic sulphate (on a finished product basis) arise from this source,even under ideal conditions~
Thus, little or no sulphate ion can be~ad~ed to these 25 systems if precipitation is to be avoided, and the addition of the magnesium ion as magnesium sulphate~ is not fe~s-ible fr~m a prod~ct st~hility sLc..dpoint Indeed, the low tole~ance of the c~mpositi~ns ~f the present invention to inorganic sulphates, produced - 30 as a ~y-product of the sulph~on)ation process frequently results in a 'desalting' step being necessary to pr~vide acceptable product stability on storage. I~here appreci~
able levels of inorganic sulphate are present, such as the 4-6% by weight of sulphate found in co~ercially 35 available paraffin sulphonates, this 'desalting' step is . .
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essential in order to avoid precipitation and deposition of inorganic sulphate from compositions in accordance -with the invention. This desalting step is normally carried out on the surfactant concerned prior to mixing with other formulation components and can be per~ormed ' by adding a lower aliphatic alcoho~,such as ethanol or isopropa~ol to the neut~alised surfa~tant in order to precipitate the sulphate as a crystalline solid. The precipitated sulphate is then remoYed by ~iltration or 10 centri~ugation. ' ' - ' ' '' As no~ea above, the formulations of the present invention are more tolerant of chloride ions than sul-phate ions and thus where chloride ions are proauced by a sulphation by-product, such as in the chlorosulphation 15 of alkyl ethers, subsequent treatment of the surfactant is normally unnecessary. The level of chloride ion , arising from this'source is normally of the order of "- 0.5~ on,a total product weight basis and pre~erred ' formulations, made using S03 su~phonation techniques, 20 are essentially free of chloride ions.
The higheI tolerance of the compositions of the invention to chloride ions leads ts the situation that provid~d the system is substantially free of inorganic sal~s prior to the i~corporation of the magnesium ion, 25,the latter can be incorporated as the c~loride salts.
' In this context 'substantially ~ree' means no more than 0.2~ by weight o~ the com~osition of inorga N c anions.
Pxeferably the compositions contain l~ss than 0.15% by weight of other inorganic anions when levels of chloride ,, 30 ion in excess of about 1~ by weight are present.' Nevertheless, the incorporation of a wat~r soluble ' magnesium salt into the formulation, whilst being permis-sible, is not a preferred technique as it increa$es the risk of phzse separation or crystalline salt deposition, 35 and, in the case of magnesium chloride, may give rise to Z~-3~

g corrosion problems in the processing equi~ment As noted a~ove, the addition of magnesium sulph2te in an amount sufficient to provide the benefits of the present invention causes crystalline salt precipitation. Even S where a salt such as magnesium acetate is employed as the source of magnesium ion, its addition to the ~ormulation may cause sulphate.and chloride salts to precipit~te., even though these may only be present at levels which would otherwise be acceptably low. Accordingly the use ..
10 of magnesium oxide or hydroxide neutralisation of oné .
or more of the anionic surfactant species is a preerred means o~ introducing the ma~nesium ion into the system.
The othex cations used in the neutralisation of the anionic surfactants may he sodium, potassium, ammonium 15 or alkanolammonium, but ammonium is a pre~erxed cation . because of its depressive effect on the chill point -``. ` . temperat~re of the compositions. Preferrea com~osltions--have chill points c.oC and in order to-achieve this at least 50% of the surfactant cations should be ammoniu~ -2~ ions..
~.- . .A desirable.componen~ of the i~en~ion is a Suas boosting agent at a level of up to 5%, preferably 3-4~
by weight. .
. The suds-promotins~agent can. be any of C12-C14 mono-25 and di C2-C3 al~anolamide, C12-Cl~ alkyl ami~es condens~d ........ with up to 15 moles of ethylene oxide per mole of amide and.tertiary amine oxides containing :a C8-C18 alkyl group.
Examples o~ the alkanol~ides ar.e coconu.~ ~L~yL
- monoetha~olamide, coconut alkyl diethanolamide and-30 coconut al~yl mono and di isopropanolamides~
: : Examples of the ethoxylated amides include coconut alkyl amide condensed with six moles of ethylene oxide, lauryl amide condensed with eight moles of ethylene oxide, myristyl amide condensed with ten moles oE ~
~5 ethy1ene oxide and coconut amide condensed with eight .

~7Z~3~1 ~ 10 -moles of ethylene oxide. Amine oxides useful in the present invention have one alkyl or hydroxyalkyl moiety of 8 to 18 carbon atoms, preferably 8 to 16 carbon atoms and two moieties selected from alkyl groups and hydroxyalkyl groups containing 1 to 3 carbon atoms. Examples of such amine oxides include dimethyloctylamine oxide, diethyl-decylamine oxide, bis - (2 - hydroxyethyl) dodecylamine oxide, dimethyldodecylamine oxide, dipropyltetradecylamine oxide, methylethylhexadecylamine oxide, and dimethyl - 2 -hydroxyoctadecylamine oxide.
A highly preferred example of the tertiary amine oxideis a C12-C14 alkyl dimethyl amine oxide in which the Cl2-Cl4 alkyl group is derived from coconut oil.
The balance of the formula comprises a hydrotrope-water system in which the hydrotrope may be urea, aCl-C3 alkanol, or a lower alkyl benzene sulphonate salt such as toluene, cumene or xylene sulphonate. The preferred hydrotrope is ethanol which is employed at from 6% to 10% by weight of the composition preferably at from 7~ to 9%.
Optional ingredients of the liquid detergent compos-itions of the invention include thickeners such as guar gum, antibacterial agents such as glutaraldehyde and Bronopo ~ (RTM), antitarnish agents such as benzoxy-triazole, heavy metal chelating agents such as EDTA or EDTMP~ perfumes and dyes. The pH of the compositions may be anywhere within the range 6-7.5 but as Manufactured the compositions normally have a pH in the range 6.6-7.3 preferably 6.6-6.9 in order to maintain colour stability.
The technique of incorporation of the magnesium ions is not thought to be critical and the compositions can be made in a number of ways. The individual anionic surfac-tants can be made as aqueous solutions of alkali metal or ammonium salts which are then mixed togerher with the hydrotrope, and the suds ~ 7 ~1 3~

booster, if this is included, following which the magnesium ion can be introduced as a water soluble salt such as the chloride or acetate. Optional minor ingredients are then added after which the pH and viscosity is adjusted. This ~ethod has the advantage of utilising conventional techniques and equipment but results in the introduction of additional chloride or acetate ions which can increase the chill point temperature (the temperature at which inorganic salts preci-pitate as crystals in the liquid).
10 An alternative method is to neutralise the alkyl ether sulphuric acid or the alkane sulphonic acid with a mag-nesium oxide or hydroxide slurry which avoids the introduction of additional inorganic anions. Although not essential, it is convenient to carry out the neutralisation of the alkyl ether sulphate in a 'heel' formed by a dispersion of the magnesium oxide or hydroxide slurry in a mixture of the hydrotrope and the other surfactant. Any alkyl benzene sulphonate present in the formulation can be neutralised separately or in the same 'heel', and the neutralised sulphonate and sulphate sur-factants together with the hydrotrope are then added to thefinal mixing tank and the suds booster and any optional ingre-dients added before the pH is adjusted as above.
The invention is illustrated in the ~ollowing examples in which the percentage of the components are by weight on the finished composition.

Example l The following composition was made up C14-C15 s-alkane sulphonate 35) incorpor+a~ing 0.44 30 C12-C13 alkyl ~EO)3 sulphate 15) p2a21s Mg ion~and Ethanol 9 Urea 3 Perfume Colour & Miscellaneous Water 37 The C14-C15 s-alkane sulphonate, available as a paste of the ammonium salt containing 60% active and 4~ ammonium sulphate was desalted by treating 58.33 parts paste with 9 parts ethan-ol and filtering off the precipitated ammonium sulphate to leave G5.23 parts of desalted paste containing 0.23 parts '~,f' . ..

` ~72~3(~

ammonium sulphate. This desalted paste was then used as a heel for the neutralisation oE the alkyl ether sulphùric acid. The latter was prepared by sulphation of an ethoxylated linear C12-C13 alcohol using an S03-air mixture and contained 0.46~
H2SO4. 2.12 parts of a 50~ slurry of magnesium hydroxide in water was added to the paste heel and then the alkyl ether sul-phuric acid was addcd with agitation. After the neutralisation of the alkyl ether sulphuric acid the remaining components were added and the pH was trimmed to 6.8 using ammonium hydroxide or citric acid. The resulting liquid detergent was a stable clear liquid with a sulphate content, expressed as (NH4)2SO4, of 0.32 by weight of the composition.
Example 2 Cl4_155~alkane sulphonate 30~ incorpor~at+ing 0.44 C12-C13 alkyl (E0)3 sulphate 10) P1ar93ts Mg iNn +and 15 Linear C11_8alkyl benzene 5) sulphonate Ethanol 9 Urea 4 Perfume Colour ~ Miscellaneous 20 Water 41 A similar procedure is followed as for Example 1. The ammon-ium alkane sulphonate surfactant is desalted to leave 57.2 parts of paste containing ammonium sulphate and 0.20 parts ammonium sulphate and the alkyl benzene~ sulphonic acid (produced by SO3 sulphonation and containing 0.11 parts H2SO4) is added to this desalted paste. The magnesium hydroxide slurry is then mixed in followed by the alkyl ether sulphuric acid. When neutralisation of the latter is complete the pH is brought up to pH 6.8 with ammonium hydroxide and th~e remainder of the ingredients added to complete the formulation. The final pro-duc~ is a clear stable liquid with a sulphate content, express-ed as (NH4)2 SO4 of 0.43~ by weight of the composition.
Example 3 35 C14-C15s-alkane sulphonate 25) incorpor+a~ing 0.44 C12_13 alkyl(EO)3 sulphate 10) 1-62 parts NH4 ion Linear C11 8alkyl benzene 5) sulphona~e ,, ,~

~7~3V

Coconu~ monoethanolamide 3 Ethanol 10 Perfumes Colour & Misc.
Water 46 The product is made up of using the procedures of Example 25 2 ~o give a clear liquid having a sulphate content expressed as (NH4)2S04 of 0.40~ by weight of the composition.

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Claims

1. An enzyme-free dishwashing liquid composition comprising a mixture of C14-C17 s-alkane sulphonates, C10-C16 alkyl ethoxy sulphates containing an average of 1-6 ethoxy groups per mole of alkyl sulphate, optionally together with an alkyl alkanolamide suds booster in a hydrotrope-water vehicle characterised in that the com-position is a clear single phase liquid comprising 20-40% alkane sulphonate 5-15% alkyl ethoxy sulphate or a mixture of alkyl ethoxy sulphate and C10-C16 alkyl benzene sulphonate 0.35-0.7 magnesium ion the composition containing no more than 1.75% by weight of chloride ion or more than 0.35% by weight of inorganic sulphate ion provided that where chloride ions are also present the level of sulphate ions should not exceed 0.25%
by weight, the counter ions other than magnesium necessary to provide a pH of 6.0-7.5 being selected from sodium, potassium, ammonium and alkanol ammonium.

2. A dishwashing liquid composition according to Claim 1 characterised in that the composition comprises 24%-34% alkane sulphonate 5%-11% alkyl ethoxy sulphate 4%-10% C11-C13 alkyl benzene sulphonate 0.4%-0.6% magnesium ion.

3. A dishwashing liquid composition according to Claim 1 characterised in that the composition is substantially free of chloride ions.

4. A dishwashing composition according to any one of Claims 1-3 wherein the counter ions other than magnesium are ammonium ions.

5. A dishwashing composition according to Claim 3 wherein the counter ions other than magnesium are sodium ions, and the level of sulphate ion is less than 0.20% by weight.